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Bad Layer Starts

Posted: Mon May 13, 2013 2:25 pm
by jbert50021
I am printing the .5mm thin wall cube. Everything is perfect except the one wall which the printer starts layers on. It is full of globs and a few holes. I tested the print with random start points but the wall was still a mess. What would cause this symptom?

Thanks,

Jason

Re: Bad Layer Starts

Posted: Mon May 13, 2013 7:44 pm
by foshon
jbert50021 wrote:I am printing the .5mm thin wall cube. Everything is perfect except the one wall which the printer starts layers on. It is full of globs and a few holes. I tested the print with random start points but the wall was still a mess. What would cause this symptom?

Thanks,

Jason

Globs and holes are symptoms of flow issues. Do this and see how it looks afterwards:

http://forum.seemecnc.com/viewtopic.php?f=54&t=1163

Re: Bad Layer Starts

Posted: Tue May 14, 2013 4:10 pm
by jbert50021
Thanks - I am done following the posts instructions. It is definitely an improvement, but there are still some globs. Is there an acceptable amount of globing or should it be perfect?

I now notice that there is an overall slant to one side. it does not look like there was one slip, but just a steady gradual slant...thoughts?

Thanks,

Jason

Re: Bad Layer Starts

Posted: Tue May 14, 2013 4:30 pm
by foshon
jbert50021 wrote:Thanks - I am done following the posts instructions. It is definitely an improvement, but there are still some globs. Is there an acceptable amount of globing or should it be perfect?

I now notice that there is an overall slant to one side. it does not look like there was one slip, but just a steady gradual slant...thoughts?

Thanks,

Jason
A picture would be very helpful.

Re: Bad Layer Starts

Posted: Wed May 15, 2013 2:09 pm
by jbert50021
20130514_211033.jpg
20130514_210734.jpg
20130514_210916.jpg

Here are some pictures

The first shows the slant to the right.
The second two show the globs on the starting side.

I hope these are clear enough - they are the best shots I could get.

Thanks,

Jason

Re: Bad Layer Starts

Posted: Wed May 15, 2013 2:50 pm
by Jimustanguitar
I was seeing this too. The imperfections are the start and stop points for each layer. The slant may just be a temperature thing. It may be warping or melting depending on your settings. 80c and 230c are good starting points.
The things you're seeing are likely a result of several variables. Do the walls measure to spec (.55mm)?

I had an issue where the wall thickness would vary from one side to another, and slicing the same stl with Cura or KISS yielded more consistent results. Have you tried this shape with either of those programs? I would recommend it as a test.

Re: Bad Layer Starts

Posted: Wed May 15, 2013 4:44 pm
by foshon
The little pock marks are fairly common. You can try speeding up retracts, increasing extruder acceleration/jerk, I have yet to find the cure-all. The slant is interesting, does it always face the same axis? Do you have a fan pointed at it?

Re: Bad Layer Starts

Posted: Wed May 15, 2013 4:56 pm
by Jimustanguitar
I know there's still a calibration tweak to administer, but later on when you're printing something cool, Cura has a feature called "Joris" that you should play with. It prints thin wall objects like this in one continuous spiral instead of many individual flat layers. This completely eliminates the need to start and stop for layers, and works really smoothly with a delta bot.